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Synchronize and blend/overlay video

post #1 of 6
Thread Starter 

Does anyone know, how to overly and synchronize 2 or more videos of athletes, for example alpine skiers, using Premiere Pro? You can see that on the TV sometimes, where 2 racers are put into one track over each other and you can compare their runs? They are using special technology on the TV, probably Dartfish. But I hope somebody has some idea how to do it in Premiere? I have put one video over the second and set the opacity to 50%. Then I moved the upper video and adjusted its size, so that the gates (the skiers were at) matched. I created keyframes for couple of gates and for each of them I repeated the same and hoped Premiere would do the rest. But the result isn't good, the skiers drive away just a moment after leaving the gate. Any tips? Thanks. Ivan
post #2 of 6
 I can help you with that. There are better apps for this, but something that might be acceptable can be done in Premiere.

If the goal is to compare your skiers' form or technique at any given point, rather than at a given time, one way to do that is to set markers at your choice frames on each clip, and then adjust the time remapping on one of the clips until the markers line up. You can get close to this by matching the durations between the first and last markers in the clips.

It would be interesting to see what would happen if you keyed out the snow behind one of the skiers, and then made him 50% opaque -- it should appear that they are on the same course at the same time.

What do you mean by "the skiers drive away just a moment after leaving the gate?"
post #3 of 6
Thread Starter 
Hi Wave,

Thank you for your answer,

But the goal is to compare skiers at any given time even if your suggestion could be interesting also. I will thing over it too. But what I am affraid is that the main problem would remain in that case also. And this is to align the videos - layers which arn't aligned because of varyiing focal lenghts and camera viewing angles at any particular time. That is what I did earlier - aligned manually videos at every gate and expected Preniere would align them inbetween. But it didn't happen, videos are disaligned after couple of frames after skier has passed the gate (the aligned picture) - that's what I have ment by  "the skiers drive away just a moment after leaving the gate"

post #4 of 6
If you're dealing with shots from different angles, with differing motion and focal lengths, then you're going to have a hard time (a gross understatement) getting this to work. The extrapolation between the markers and gates on each clip will necessarily be different. You might be stuck with moving the clips side-by-side and synchronizing the start.
post #5 of 6
The optimal tool for what I think you're trying to do is performed by motion-tracking software. Adobe After Effects has motion-tracking. I don't think PremierePro does. On the Mac, Final Cut Pro's motion-tracker filter, or Apple's now-discontinued Shake would do it. However, this task is extremely CPU-intensive. A few seconds may take a few hours to render. Also, I'm not sure how you would synch the action. These are actually pretty sophisticated techniques, beyond my small area of post-production knowledge.

In televised broadcasts, they have expensive, dedicated boxes to perform these kinds of exotic tasks. The computers used to generate the first-down graphics overlays in NFL games, I'm told, takes an entire truck!
post #6 of 6
Absolutely, If you've got After Effects and Premiere, well, that changes everything. You're set. Do your effects in After Effects, then edit in Premiere.
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